A giant isopod is any of the almost 20 species of large crustaceans related to the shrimp and crabs in the genus Bathynomus. They are thought to be abundant in cold, deep waters of the Atlantic, Pacific and Indian Oceans. Giant isopods are of little interest to most commercial fisheries owing to the typical scarcity of catches and because ensnared isopods are usually scavenged beyond marketability before they are recovered. The species are noted for resemblance to the common woodlouse or pill bug, to which they are related. Giant isopods are important scavengers in the deep-sea benthic environment; they are mainly found from the gloomy sublittoral zone at a depth of 560 feet to the pitch darkness of the bathypelagic zone at 7,020 feet, where pressures are high and temperatures are very low (down to about 39∞F). They are thought to prefer a muddy or clay substrate and lead solitary lives.